1. Field of the Invention
An aspect of this disclosure relates to a film deposition method, a storage medium, and a film deposition apparatus.
2. Description of the Related Art
There exists a technology where a high dielectric constant material is used for an insulating layer of a memory cell of a semiconductor memory to increase the capacity of the semiconductor memory. Zirconium oxide (ZrO) is an example of a high dielectric constant material. ZrO has a dielectric constant of about 24 to 40, but has a low dielectric strength. Japanese Laid-Open Patent Publication No. 2011-18707 discloses a technology where the dielectric strength of ZrO is improved by adding aluminum (Al) to ZrO.
Meanwhile, there is a trend to increase the diameter of a semiconductor wafer (which is hereafter referred to as a “substrate”) to reduce the costs of a semiconductor memory. Here, increasing the diameter of a substrate makes it necessary to improve the uniformity of a film within a surface of the substrate. For this purpose, for example, a film deposition method called an atomic layer deposition (ALD) method (or a molecular layer deposition (MLD) method) is used.
In the ALD method, one (reaction gas A) of two types of reaction gases that react with each other is adsorbed onto a substrate surface, another one (reaction gas B) of the two types of reaction gases is caused to react with the reaction gas A adsorbed onto the substrate surface, and these steps are repeated. Through this process, a reaction product of the reaction gas A and the reaction gas B is generated on the substrate surface, and a thin film made of the reaction product is formed on the substrate surface.
When, for example, the ALD method is performed with a batch-type film deposition apparatus, the reaction gas A is supplied into a process chamber where substrates are placed so that the reaction gas A is adsorbed onto the surfaces of the substrates. Next, the process chamber is evacuated or purged. Then, the reaction gas B is supplied into the process chamber so that the reaction gas A adsorbed onto the surfaces of the substrates reacts with the reaction gas B. As a result, a reaction product is generated on the surfaces of the substrates. The process chamber is evacuated or purged again, and the above process is repeated until a thin film with a desired thickness is formed on each of the substrates.
Thus, when a film deposition process according to the ALD method is performed with a batch-type film deposition apparatus, the film deposition process needs to include steps for supplying and purging the reaction gas and for supplying and purging the reaction gas B. Accordingly, it generally takes time to form a thin film according to the ALD method using a batch-type film deposition apparatus.
On the other hand, with a rotary-table film deposition apparatus where substrates are placed and processed on a rotary table, it is possible to reduce time necessary for a film deposition process.
In the rotary-table film deposition apparatus, the rotary table is rotated to cause each substrate to sequentially pass through a supply area A where the reaction gas A is supplied, a separation area, and a supply area B where the reaction gas B is supplied. The reaction gas A is adsorbed onto the substrate surface in the supply area A, and is caused to react with the reaction gas B in the supply area B.
Here, with the rotary-table film deposition apparatus, if the cycle of rotation of the rotary table is in synchronization with the timing when the reaction gas A or the reaction gas B is supplied, the amount of the reaction gas A or the reaction gas B adsorbed may vary depending on the substrates. That is, with the rotary-table film deposition apparatus where the reaction gas A or the reaction gas B is supplied directly to one substrate at a time, the controllability of a film deposition process and the uniformity of a thin film on each substrate and the uniformity of thin films on multiple substrates may be reduced.